pls helpp i dont get it cuz i wasnt listing -_-

Answer: 54 inches
Step-by-step explanation:
Let's take the equation for the area of a right triangle
[tex]A=\frac{a*b}{2} \\\\A=\frac{12*9}{2} \\\\A=\frac{108}{2}\\\\A=54[/tex]
A=a*b/2
A=12*9/2
A=108/2
A=54